Recently, as a processing apparatus for processing a device forming surface of a semiconductor wafer, a chemical mechanical polishing (CMP) apparatus having both a chemical operation and a mechanical operation has been adopted.
Meanwhile, a substrate formed from a hard brittle material such as sapphire, SiC, GaN, and diamond recently attracting attention as a next generation semiconductor substrate is chemically stable. Therefore, even though a general chemical mechanical polishing method is utilized, the chemical operation is extremely insignificant, compared to a case of using Si. Thus, a polishing rate becomes small.
One method of polishing a processing target substance while performing irradiation of an ultraviolet ray includes setting pressure of a processing atmosphere including oxygen to be higher than atmospheric pressure and adopting a slurry including particles of titania in a processing atmosphere (for example, refer to Pamphlet of International Publication No. 2007-063873 WO).
In addition, a polishing method has been proposed. In the method, a polishing surface plate formed from quartz and having lattice grooves on the external surface is adopted, solid photocatalyst particles are embedded in the lattice grooves, a polishing target surface of the substrate is pressed to the external surface of the polishing surface plate at high pressure, the polishing target surface of the substrate is irradiated with an ultraviolet ray which is transmitted through the polishing surface plate from the rear surface of the polishing surface plate, and the substrate is oscillated relatively with respect to the polishing surface plate while at least any one between the external surface of the polishing surface plate and the polishing target surface of the substrate is heated by performing irradiation of infrared light (for example, refer to Pamphlet of International Publication No. 2007-007683 WO).